New paper on the effects of bilingualism on the volume of the hippocampus in older adults, in Brain Structure and Function

Voits, T., Robson, H., Rothman, J., & Pliatsikas, C. (2022). The effects of bilingualism on hippocampal volume in ageing bilinguals. Brain Structure and Function. DOI: 10.1007/s00429-021-02436-z

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Long-term management of more than one language has been argued to contribute to changes in brain and cognition. This has been particularly well documented in older age, where bilingualism has been linked to protective effects against neurocognitive decline. Since memory difficulties are key aspects of this decline, herein we examine potential effects of bilingualism on the hippocampus, a brain structure related to memory that is particularly vulnerable to cognitive ageing. Hippocampal volume has been shown to increase as a result of second language learning and use in younger adults. However, it is unknown if this is maintained throughout the lifespan. We examine hippocampal volume and episodic memory performance in a participant sample consisting of healthy older individuals with a wide range of experiences in exposure and using a second language. Results reveal greater hippocampal volume calibrated to degree of quantified dual language use. Our results mirror those of immersive active bilingualism in younger populations, suggesting that long-term active bilingualism leads to neuroprotective effects in the hippocampus. We discuss this in the context of literature proposing bilingualism-induced brain reserve in the older age.


New preprint: The dynamic effects of bilingualism on subcortical structures

Korenar, M., Treffers-Daller, J., & Pliatsikas, C. (2021): Bilingual experiences induce dynamic structural changes to basal ganglia and the thalamus

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Bilingualism has been linked to structural adaptations of subcortical brain regions that are important nodes in controlling of multiple languages. However, research on the location and extent of these adaptations has yielded variable patterns. Existing literature on bilingualism-induced brain adaptations has so far largely overseen evidence from other domains that experience-based structural neuroplasticity often triggers non-linear adaptations which follow expansion-renormalisation trajectories. Here we use generalised additive mixed models (GAMMs) to investigate the non-linear effects of quantified bilingual experiences on the basal ganglia and thalamus in a sample of bilinguals with wide range of bilingual experiences. Our results revealed that volumes of bilateral caudate nuclei and accumbens were positively related to bilingual experiences in a non-linear pattern, with increases followed by decreases, in the most experienced bilinguals, suggesting a return to baseline volume at higher levels of bilingual experience. Moreover, volumes of putamen and thalamus were positively linearly predicted by bilingual experiences. The results offer the first direct evidence that bilingualism, similarly to other cognitively demanding skills, leads to dynamic subcortical structural adaptations which can be nonlinear, in line with expansion-renormalisation models of experience-dependent neuroplasticity

More good news from the lab!

First of all, we have a new doctor in the house! (Now Dr) Michal Korenar succesfully defended his thesis this week, and passed without corrections! Congratulations Dr Korenar!

Michal will soon leave the lab, but the show must go on! So earlier this term we welcomed our new recruit, Alex Sheehan! Alex’s PhD is funded by the ESRC SeNSS DTP, and he will invesigate will investigate the impact of linguistic experiences on structural and functional brain connectivity, and neural efficiency. We are looking forward to this very interesting project!

Proudly presenting… Dr Najla Alrwaita!

Join me in congratualting (now Dr.!) Najla Alrwaita for succesfully defending her PhD thesis last week! Najla’s thesis was on the effects of diglossia on executive functions. Special rhanks to the examiners Dr Andrea Krott and Dr Ian Cunnings.

Congratulations Najla! Another bird flies the lab nest! Such a shame we still can’t have a proper (in person!) celebration, but hopefully we will soon!

Our lab at the International Symposium on Bilingualism, in July 2021! #ISB13

Our lab participates in this year’s ISB conference with seven presentations! Come visit us at the times below (all UK times):

-11/07, 14.15: Christos Pliatsikas, Vincent DeLuca, Sergio Pereira Soares, Toms Voits and Jason Rothman: Bilingualism modulates metabolite concentrations in the healthy brain 

Part of the thematic session TS24: Synergies & confrontations: socio- and psycholinguistic, cognitive and neuroscientific approaches to bilingualism 

-11/07, 14.15: Najla Alrwaita, Lotte Meteyard, Carmel Houston-Price and Christos Pliatsikas: Is there an effect of diglossia on cognition? An investigation of the relationship between diglossia and executive functions in young adults

Part of the open session OS10: Psycholinguistics: the cognitive aspects of bilingualism (III)

-12/07, 8:00: Michal Korenar, Jeanine Treffers-Daller and Christos Pliatsikas: Bilingualism and creativity: The effects of bilingual experiences of interpreters and translators on creative thinking

Part of the open session OS12: Translation/ Interpretation / Mediation

-13/07, 08:00: Jia’en Yee, Ngee Thai Yap, Douglas Saddy, Christos Pliatsikas: Subcortical restructuring with increasing language experience: insights from bilinguals and trilinguals 

Part of the open session OS18: Bilingualism and the brain

-13/07, 15.30: Nan Xu Rattanasone, Jae-Hyun Kim, Christos Pliatsikas: English vocabulary predicts the acquisition of grammatical inflections in Mandarin-speaking preschoolers

Part of the open session OS21: Early second language acquisition & learning (I)

-14/07, 9:45: Michal Korenar, Jeanine Treffers-Daller and Christos Pliatsikas: Subcortical adaptations in interpreters and translators compared to multilingual controls, and their relationship to multilingual experiences 

Part of the thematic session TS25: The intersection between interpreting and the language hierarchy

-14/07, 13:00: Toms Voits, Jason Rothman, Holly Robson, Marco Calabria, Lidón Marín Marín, Victor Costumero, Naiara Aguirre, Christos Pliatsikas: Bilingualism-related neural adaptations in Mild Cognitive Impairment patients are modulated by language experiences 

Part of the open session OS17: Cognitive and language impairments in bilingual speakers

More details about the conference can be found here:

If you wish to register to ISB, please write to for further instructions.

New preprint: Executive functions in Arabic diglossic young adults

Alrwaita, N., Meteyard, L., Houston-price, C., & Pliatsikas, C. (2021): Is there an effect of diglossia on cognition? An investigation of the relationship between diglossia and Executive Functions in young adults.

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Recent studies investigating whether bilingualism has effects on cognitive abilities beyond language have produced mixed results, with evidence from young adults typically showing no effects. These inconclusive patterns have been attributed to many uncontrolled factors, including linguistic similarity and the conversational contexts the bilinguals find themselves in, including the opportunities they get to switch between their languages. In this study, we focus on the effects on cognition of diglossia, a linguistic situation where two varieties of the same language are spoken in different and clearly separable contexts. We used linear mixed models to compare 32 Arabic diglossic young adults, and 38 English monolinguals on cognitive tasks assessing the Executive Functions domains of inhibition, switching and working memory. Results revealed that, despite both groups performing as expected on all tasks, there were no effects of diglossia on their performance in any of these domains. These results are discussed in relation to the Adaptive Control Hypothesis. Considering that this is the first study to investigate the diglossic advantages in Arabic, we propose that any effects on Executive Functions that may be attributed to the use of more than one language or language variety should not be expected when the two are used in exclusive contexts with limited opportunity to switch between them.

New paper on metabolite concentrations in the bilingual brain, in Scientific Reports

Pliatsikas, C., Pereira-Soares, S.M., Voits, T., Deluca, V., & Rothman, J. (2021): Bilingualism is a long-term cognitively challenging experience that modulates metabolite concentrations in the healthy brain. Scientific Reports, 11, 7090.

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Cognitively demanding experiences, including complex skill acquisition and processing, have been shown to induce brain adaptations, at least at the macroscopic level, e.g. on brain volume and/or functional connectivity. However, the neurobiological bases of these adaptations, including at the cellular level, are unclear and understudied. Here we use bilingualism as a case study to investigate the metabolic correlates of experience-based brain adaptations. We employ Magnetic Resonance Spectroscopy to measure metabolite concentrations in the basal ganglia, a region critical to language control which is reshaped by bilingualism. Our results show increased myo-Inositol and decreased N-acetyl aspartate concentrations in bilinguals compared to monolinguals. Both metabolites are linked to synaptic pruning, a process underlying experience-based brain restructuring. Interestingly, both concentrations correlate with relative amount of bilingual engagement. This suggests that degree of long-term cognitive experiences matters at the level of metabolic concentrations, which might accompany, if not drive, macroscopic brain adaptations.